Conventional method for allocating time slots for communication by time division wireless communication performs allocation according to random values or performs allocation in accordance with unique information of terminals (see Japanese Patent Laid-Open Publication No. 9-238100). A method is also known in which a plurality of relay terminals are made to use the same time-division slot that is previously allocated to implement relay transmission (see Japanese Patent Laid-Open Publication No. 2002-171215). In addition, a method is known in which a plurality of relay stations are allocated to the same time slot and the optimal relay station is selected according to the radio wave intensity (see Japanese Patent Laid-Open Publication No. 2004-328665).
In recent years, wireless communication is also being utilized for communication between domestic information devices. As a method that simply and effectively implements this kind of wireless communication between domestic information devices, a time division relayed communication method has been proposed in which information devices perform transmission of wireless data to each other using a time division system. This kind of domestic wireless communication principally involves wireless communication of stream data for which real-time performance is required, such as video data or audio data. Therefore, there is also an increasing necessity for time division relayed communication method to transmit data with lower delays and constant delays, without having to retransmit data due to the occurrence of errors or the like.
When performing relay transmission using a conventional time-division communication method, time slots for communication are randomly allocated for each terminal or, alternatively, time slots for communication are suitably allocated based on individual information of the communication terminals or the like. There is therefore the problem that when the communication quality with the communication terminal on the side starting relay transmission is poor and an error occurs, the data of poor quality in which the error occurred is transmitted in sequence by relay transmission and the communication quality of the overall time division relayed communication system deteriorates.
Further, once time slots are allocated, those time slots are kept without any change even if the communication situation changes. Therefore, cases arise in which, even though communication quality is favorable at first and relay transmission is possible, the communication quality between communication terminals carrying out relay transmission deteriorates due to the appearance of an obstacle or the movement of a relay terminal and consequently an error occurs. In this case also, there is the problem that poor quality data in which an error occurred is transmitted sequentially by relay transmission and the communication quality of the overall time division relayed communication system deteriorates.
In conventional packet communication, as one method to solve this problem, the capacity of a reception buffer is enlarged so that the data for a previously fixed time period is stored and delayed, and resending of the data is executed within the delay time to execute recovery. As another method, the error tolerance of wireless communication is improved by lowering the rate of data that is communicated so that an error does not occur. However, it has been difficult to implement communication with low delays and constant delays in stream data communication because the data rate is fixed.